Recovery of volatile organic solids



Patented a... 4. 19 27.

UNITED STA ES PATE Nr OFFICE.

JEAN HENRY nnnenar, or rams, l mon, assrenon T0 nnnonn'r conroma'Io ormnmca, or WILMINGTON, DELAWARE, a CORPORATION or nnmwann.

nncovnnv orvom'rmn ORGANIC somns.

Rb Drawing. Application and me 20, 1e21, Serial No. 479,149, and inFrance March 19, 1920.-

There is on file in the United States,

plication for Patent Serial No. 431,526, filed December 17, 1920,entitled Process for the recovery of camphor and naphthalene co'n tainedin gaseous mixtures. In said appl1- cation there is described a processfor the recovery of vapors of camphor and naphtha lene contained ingaseous mixtures, by treating with an absorbent consisting essentiallyof phenolic bodies, such as carbolic acid or cresylic. acids or. both.After distilling off volatile liquid solvents, and preferably afterrepeating the absorption andthe distilling oit of volatile solvents anumber of times,

the phenolic liquid becomes charged with camphor, say up to 10%, more orless.

Then follows a separation of the absorbent and absorbed volatile organicsolid products; (a) as by injecting steam which allows the extraction ofalmost the entire.

amount of camphor and/or naphthalene; or (71) as by precipitation withcaustic alkali which results in the formation of alkali.

' cover vapors of the camphor and vapors of the liquid solvents, such asether, alcohol, acetone, amyl acetate, etc., and by subsequent indirectheating of the absorbent containing the absorbedvapors, the liquidsolvents are driven off completely with only a small part of the camphor(slightly volatile organic solid) with the result that as the absorbentis used again and again, it ultimately becomes charged with camphor, upto about 10% of its weight. At this stage, the viscosity of theabsorbent liquid has considerably increased (from the original).

There is referred to in said application the recovery of the camphor andthe regeneration of the phenolic absorbent. The elimination of thecamphor is best effected by treating the camphor-laden absorbent (afterthe liquid solvents have been more or less driven off) With causticsoda, thus throwing out or precipitating the camphor-the soda nd theabsorbent combining to form the sodium salts, as above indicated. Insaid application there is also suggested that the soant, or may beregenerated by treatment with an acid; or be'tter with an acid salt;

andexperiments have shown that in the regeneration process ust referredto, carbonic acid (carbonic acidv gas) can conveniently be used in placeof both (a) acids (such as the waste residual acids from the manufactureof nitrocellulose, nitroderivatives, etc.) anl (b) the acid salts suchas bisulphate of so a.

The-present invention thus depends upon caused by any suitable means tocome into' 'mtlmate contact, as by bubbling, or scrubhing, with theaqueous solution of the sodium salt of the phenolic absorbent,liberating the absorbent, and this allows for the subsequent'reemployment of the absorbentfor like sodium bisulphate. .M'yfurther tests' absorption purposes and also gives rise to the formationof an'aqueous solution of sodium carbonate. This carbonate solution canbe utilized to obtain solidsodium'carbonate; or, again it may be madeinto caustic soda by proper treatment.

By conversion of the by-product solution I of sodium carbonate intocaustic soda there is in effect regenerated the caustic soda which" isused in the transformation'of the phenolic absorbent into its sodiumsalt and which transformation permits the entrainment, the carrying overeither mechanically or in vapor form, the sweeping out of the mass, orthe separating and carrying up to the surface of the mass, of camphor bysteam. In other words, the use of carbonic acid, to wit, carbonic acidgaswhich (particularly in the dilute state in which it may be used) is acommon and cheap roduct-liberates the phenolic absorbent an producessodium carbonate and this followed by-a subsequent causticizing of thesodium carbonate leads to' a continuous cycle which develops in such away as to successively recover the more'costly products; that is to say,camphor, phenolic absorbent, andfinall soda, and this by con-. sununalsoofi'ers the advantage of. not necessitating the haniilling andstoring of containers 801 o A I Itw ll be manifest that the emstence ofa cheap an very common productl i like limestone. The use of carbonloacid" containers holding acids, in places such as those for themanufacture of celluloid and similar plastic materials-smokeless powdercontaining camphor for example-can ive rise to accidents or at least totrouble.

oreover, the volumes of products to be treated are, all things equal,reduced about one-half by the use of carbonic acid and the use of. thisacid also allows the eti'ecting of the operations of the vregenerationof the phenolic absorbent in iron, cement or tarred wooden tanks, whichare relatively cheap, compared to lead-lined tanks which would generallybe used in treating thetphenatc solutions with sulfuric or like acid.

What I claim is: I y 1. In the recovery of camphor, the steps ofprecipitating camphor in an alkali metal 'phenolate solution, separatingcamphor from alkali, which effectsv precipitation of thecamphor and'theconversion of the phenolic bodies into alkali metal salts thereof,removing the salts, and subjecting the same when in an aqueous solutionto the action of a reagent containing carbon dioxid until the phenolsare set free in a state' suitable for reemployment in the absorptionprocess.

3. A process for the recovery of volatile solvents wherein there isutilized an absorbent phenolic liquid that is repeatedly used forabsorbing the solvents and from which the absorbed volatilized normallyliquid solvents are eliminated and which process is employed for therecovery of camphor vapors mixed with vapors of volatile solvents to berecovered. some of which camphor is subsequently eliminated but part ofwhich remains as a contaminatingagent in the absorbent liquid even aftersaid eliminatingoperation, which process is characterized by theregeneration of the absorbent liquid and the conversion of the" topermit its repeated use in the process;

'by'treating the phenolic absorbent containing'camphor with a causticalkali solution which effects a throwing out of theca nphor henols inthe absorbent into alkali metal sa treating withsteam to cause theseparation of camphor, subjecting said salts "of the phenols,- inaqueous solution, to the'action for the recovery of volats of thephenols,

of carbon diox'id until the phenols are liberated, wherebythe latter canbe reused in the process. t

4; A processfor' the recovery of volatile solvents wherein there, isutilized phenolic absorbent liquid that is used again and again forabsorbin the solvents and from which the absorbe volatile liquidsolvents are eliminated, after each absorbing operation, and whichprocess is employed for the re covery of camphor vapors mixed with thevapors of liquid volatile solvents to be recovered, some of whichcamphor is subsequently eliminated from the absorbent, bdt

partof' which remains in the absorbent 30 liquid even after thedistilling operation, which process is characterized by the regenerationof the absorbent to permit its repeated use in the-process; such reeneration comprising treating with alkali ydroxide solution, thuseffecting a throwing out of the camphor' and the conversion of thephenols in the liquid into solublesaltsthereof, and

subsequently separating said camphor from the said salts, and treatingthe liquid residue with CO v i 1 5. .The repeated employment of phenolsfor the recovery of mixed vapors of volatile solvents and camphor by arocess involving the absorbing of the mixed vapors by phenols,'thesubsequent subjecting of the absorbent to distillation in a manner todriveof? th absorbed volatile solvents and also some of the absorbedcamphor, re eating said cycle of operation until it is a visable toregenerate the absorbent and afterdistillation then treating theabsorbent with an aqueous solution of caustic soda until the sodiumphenolates are formed and the cam phor is precipitated, injecting steamintothe I resultant mass and separating the camphor outof the sodiumphenolates, withdrawing the sodium phenolates, subjecting an aqueous Isolution thereof, to intimate contact with carbonic acid gas until thephenols are freed or liberated, and subsequently reintroducing the freedphenols into the process for further and repeated use. 7

6. The repeated employment ofphenols for the recovery of camphor va orsby a process which includes the absorbing of the vapors by phenols,thereafter subjecting the ,phenols to a distilling operation whichdrives off a partonly of the absorbed camphor, and continuing andrepeating the cycle until it is advisable to specially treat thephenols, for the separation .of camphor I which special treatment iscarried outafter a distilling operation and before a succeed ingabsorption operation, and involves subjetting the phenolsito" the actionof, an a We ous solution of caustic alkalbuntil al ali metal phenolatesare formed and until the camphpr therein is "precipitated, injectingsteam into the resulting mass and separating no I . mixtures by aprocess involvin alternately absorbing vapors by the pheno ic absorbentbodies, and distilling off from the absorbent a part of said absorbedvolatile organic solid, and continuing said steps until the absorbentcontains a substantial percentage of said volatile organic solid,treating the absorbent by caustic alkali to form a phenolate and toprecipitate the volatile organic solid, separating the volatile organicsolid from the phenolate, regenerating the phenolic absorbent from thephenolate by treatment with a fiuid containing carbon dioxid, andreturning the regenerated absorbent in the process.

8. The repeated employment of absorbent bodies having phenolic functionsfor the obtaining or recovering of vapors of volatile organic solidsfrom gaseous mixtures by a process involving the absorbing of the vaporsby the absorbent bodies having phenolic functions followed by adistilling from the absorbent of a part only of the'absorbed volatileorganic substance and the continuance of the use of said absorbent inthe repeating of the steps above recited, the treating of the absorbentby a solution of caustic soda in a manner to form sodium phenolates fromthe phenols in the absorbent and the throwing out of the absorbedvolatile organic substances, the separating of the volatile or ganicsubstances and the sodium phenolates, the subsequent regeneration of thephenolates by the utilization of carbonic acid in a manner to effect aliberation of the phenols and again, in the process, employing thephenols which impart to the absorbent the phenolic functions. I

9; The process of separating camphor' from phenols involving thetreatment of the phenols containing camphor with an aqueous solution ofcaustic fixed alkali until alkali phenolates are formed, and until thecamphor therein isprecipitated, injecting steam into the resulting massand se aratof precipitating camphor in .an alkali metal phenolate soluton, separating said camphor from sald solutlon by steam distillation,and

thereafter treating said solution with carbon dioxld.

Specification signedthis 1st day of .June A. D., 1921. I

JEAN HENRY BREGEAT. [us] ing out the camphor, and carbonating t e rea'sulting liquid.

